Continuous-time filters find use in applications involving, but not limited to, disk drive readers, data converters, and wireless radio frequency (RF) transceivers. The monolithic integration hurdle, previously posed by bulky passive RLC filters, was overcome through the evolution of semiconductor devices that enabled higher order filters to be implemented using RC (R—resistor, and C—capacitor) and active elements such as transistors, thereby eliminating the need for bulky inductors (L).
Integrated analog filters using the abovementioned active elements, or alternately, active filters, have found use in radio frequency (RF) transceivers used in cellular communication. Specifically, active filters have been used for band selection and jammer rejection in RF transceivers. Target filtering applications such as wireless transceivers may also require the integration of multiple radios on a single chip or a system. The presence of multiple radios may require high orders of filtering to suppress interference from one radio to another. For example, harmonic frequencies of one radio may be close to the signal band of another radio. The area savings may go hand in hand with power savings in integrated systems (e.g., System-on-Chip (SoC)) that demand smaller space and low power consumption.